The Great War’s legacy to New Zealand is huge. On the Western Front, however, where New Zealand was busiest, little on the ground recalls our Expeditionary Force’s deeds. One needs to look underground for the heritage that links our forces with those years: caverns under Arras city, shaped by our military engineers.

Trench warfare owed much to sieges of old when tunnelling undermined fortress walls. In trench warfare, before the tank, it was again considered by the Allies for breaking the German lines. Mining was successful at Gallipoli; in 1915, the British commanders called for it on the Western Front.

Tunnellers dug under enemy trenches, then detonated with explosives to disrupt the enemy’s defences. Counter-mining also developed, where each side listened for the other’s digging and dug furiously to disrupt it. Tunnelling required technical know-how: how to use sensitive electronics and breathing equipment, knowledge of structural forces, and a grasp of chemistry when using explosives (which produces toxic gasses in confined spaces).

As this work was also labour-hungry, specialist Royal Engineer companies were formed. Australia had four and Canada three; New Zealand had just one of the 33 tunnelling companies formed.

Four hundred miners and labourers assembled at Avondale, Auckland, in October 1915. They included 50 organised labour leaders (union secretaries or committee members) who were strong unionists, but the appointment of regular commander Major John Duigan kept a lid on dissent. During the War only one tunneller was sentenced to death for desertion, soon commuted to imprisonment. Happier men, it was found, dug further.

After a month’s training in Britain, the New Zealand Tunnelling Company moved to northern France. The company was not with the New Zealand Division but under command of the British Third Army; the British had up to five armies on the Western Front. The New Zealand Division was soon given a challenge that would make its name.

Over 20 large underground quarries dating to antiquity lay beneath the Arras suburbs of Ronville and St Saveur. From these caverns, blocks of chalk stone had long been extracted for buildings in town, some of them 400 years old.

The British command felt these caverns could be used to break the deadlock if connected underground and given exits close to the German trenches, a kilometre to the east. Troops would enter via Arras’s main sewer, station and cellars.

The New Zealand company took over this sector from British tunnellers in November 1916. The next five months preparing for the offensive were of unremitting toil.

They connected the caverns to the sewer, then drove forward to add machine-gun posts, shelters, magazines, gas-doors and secret exits near the front. In stretches over two kilometres long, New Zealanders also laid tramlines, water pipes, signal cables and electric power. They completed an underground Advanced Dressing Station with operating facilities and repaired shallow tunnels “crumped” (caved-in) by enemy shelling.

An innate desire for innovation led the New Zealanders to modify some techniques. The British imported sawn planks to line the interior of their tunnels. The New Zealand company milled logs from local woods (also salvaging timber from demolitions). This required setting up sawmills in the area, and reduced demand for a scarce commodity. They also timbered less often than the British – every two or three metres, with posts up to 30 centimetres wide, with thinner poles on top of the cross-pieces as lagging.

New Zealanders chose a different tunnel profile to better suit our beefier men who would be swinging their pickaxes. It was cut 15 centimetres wider and 50 centimetres higher – yet the company often exceeded the neighbouring companies in distance-tunnelled-per-man.

In the chalk caverns, natural crumbling had raised the ceilings to a height where they and the supporting columns were difficult to brace. Spoil from tunnel excavations was used to raise the floor, bringing the ceiling within workable height.

Another innovation from the New Zealanders involved getting new entrances down to the depth from where the horizontal tunnels departed (as deep as 30 metres, just above the water table). The British had dug vertical shafts, but the New Zealand company started further back and cut inclines. These were quicker and made the disposal of spoil and loading explosives easier, using a hand-pushed tramway. This work was usually done by infantry, including Māori, “Jocks” (Scots) and “Bantams” (diminutive Tommies).

Getting the best out of men, many in their 40s, was the role of the officers. Most were engineers from mining firms, city councils or the Public Works Department (PWD). Some were pre-war Territorials. Major Duigan was replaced in January 1917 by Major Hugh Vickerman, a PWD man. For his deft handling of the unit (sometimes over 500-strong), Major Vickerman was decorated. After Arras, he acted as the Third Army’s Controller of Mines.

A later acting commander, Captain Dudley Holmes, was from engineering royalty. His father Robert West Holmes was the legendary public works Engineer-in-Chief (of Raurimu Spiral fame) who was, at the time, also President of the New Zealand Society of Civil Engineers (NZSCE). Captain Holmes later oversaw another notable engineering feat by the company – building the Havrincourt Bridge. No doubt NZSCE meetings buzzed with news from the front and celebrated the reputation earned by New Zealand engineers.

In the big Arras push in April 1917, the New Zealanders ran the pumps and generators. They detonated explosives in tunnels under enemy lines, and opened hidden exits for troops to storm the Germans. From these, thousands of troops ascended like devils from hell: the battle was successful, gaining over 7,000 metres of ground.

Heritage is all about culture and the New Zealand Tunnelling Company imprinted its culture on the Arras caverns. In the Ronville system nine caves were named after New Zealand towns, including Russell, Auckland and New Plymouth. Tunnellers scratched their names and units into the chalk walls. This work cemented the epithet “Diggers” on New Zealand soldiers. A tunnelling museum opened in la Carrière Wellington (the Wellington Quarry). In New Zealand, more digging would commemorate a century since the Great War: trenching Buckle St under Wellington’s Pukeahu National War Memorial Park. On 27 September 2014, it was fitting the underpass was named “Arras Tunnel 2014”. Descendents of New Zealand tunnellers, not quite devils from hell, were the first to walk through.

Documenting the Arras Tunnels

Peter Cooke has been commissioned by John Douglas Publishing to write the tunnellers’ story as a book, and has also been engaged by the Royal New Zealand Engineers to write their Corps’ history.

Brett Killington is a New Zealand photographer who has been documenting the space under Arras for the past four years. His work will be exhibited in a number of countries in the next few years. He is currently looking for companies in New Zealand that may be interested in exhibiting his work. More images from this series can be seen on his website www.64stops.com